Apparatus for selective application of electrophoretic coatings

ABSTRACT

ELECTROPHORETIC COATINGS ARE FORMED SELECTIVELY UPON SURFACES RECEPTIVE TO COATING. THE COATING SUSPENSION IS EXTRUDED IN A SMALL VISCOUS MASS AT THE SELECTED SURFACE SITE AND A COATING DEPOSIT IS FORMED THE THE MASS BY ELECTROPHORESIS. AND HAND TOOL DEVISED FOR THIS PURPOSE INCLUDES A RESILIENTLY DEFORMABLE HAND MANIPULATABLE VESSEL ASSEMBLY HAVING A CAPPED FILLER OPENING FOR RECEIVING SUPPLIES OF THE COATING SUSPENSION FLUID AND A DISPENSING DUCT FOR EXTRUDING THE SUSPENSION. THE DUCT INCLUDES A FLEXIBLE INSULATED NOZZLE ELEMENT CONNECTED WITH THE MAIN RESERVOIR STRUCTURE THROUGH A RIGID CONDUCTIVE TUBULAR ELEMENT WHICH ALSO ACTS AS AN ELECTROPHORESIS ELECTRODE. THE TUBULAR ELEMENT AND NOZZLE ELEMENT TAPER PROGRESSIVELY TOWARDS A SMALL OPENING IN THE NOZZLE AT WHICH THE COATING FLUID IS DISPENSED WITH CAPILLARITY, THE OPENING IN THE NOZZLE IS ADAPTED TO CONTACT AND CONFORM TOTHE RECEPTIVE SURFACE AT THE SITE SELECTED FOR COATING. THE TOOL INCLUDES A BATTERY COMPARTMENT AND EXTERNAL CONNECTION LEAD FOR SUPPLYING VOLTAGE TO GENERATE THE ELECTROPHORETIC DEPOSITS.

May 16, 1972 v AULETTA ETAL 3,663,415

APPARATUS FOR SELECTIVE APPLICATLON 0F ELECTROPHOREIIG COATINGS Filed Dec 4 1969 INVENTORS LUCIEN V. AULETTA YUNGIL KIM ANDREW M. SIMON ATTORNEY United States Patent O 3,663,415 APPARATUS FOR SELECTIVE APPLICATION OF ELECTROPHORETIC COATINGS Lucien V. Auletta, Wappingers Falls, Yungil Kim, Poughkeepsie, and Andrew M. Simon, Wappingers Falls, N.Y., assignors to International Business Machines Corporation, Armonk, N.Y.

Filed Dec. 4, 1969, Ser. No. 882,070 Int. Cl. B01k /02; C23b 13/00 US. Cl. 204-299 Claims ABSTRACT OF THE DISCLOSURE Electrophoretic coatings are formed selectively upo n surfaces receptive to coating. The coating suspension extruded in a small viscous mass at the selected surface site and a coating deposit is formed from the the mass by electrophoresis. A hand tool devised for this purpose includes a resiliently deformable hand manipulatable vessel assembly having a capped tiller opening for receiving supplies of the coating suspension fluid and a dispensing duct for extruding the suspension. The duct includes a flexible insulated nozzle element connected with the main reservoir structure through a rigid conductive tubular element which also acts as an electrophoresis electrode. The tubular element and nozzle element taper progressively towards a small opening in the nozzle at which the coating fluid is dispensed with capillarity. The opening in the nozzle is adapted to contact and conform to the receptive surface at the site selected for coating. The tool includes a battery compartment and external connection lead for supplying voltage to generate the electrophoretic deposits.

BACKGROUND OF THE INVENTION (1) Field of the invention The invention relates to a method and apparatus for forming electrophoretic coating deposits selectively at small area sites on surfaces receptive to such coating.

(2) Description of the prior art In the electrophoretic coating arts it is known generally to form coatings by covering entire part surfaces wuh the coating suspension or solution. This is accomplished either by immersing the part in a bath of the solution or by dispensing an unconfined stream of the solution over the part.

To form coatings selectively ordinary practice is to mask the part which is to be coated so that only the selected surface sites are exposed to the solution. This of course is a costly and diflicult procedure with only limited utility. Certainly it would not be useful for purposes presently contemplated; e.g. field repair and touchup of coated microelectronic devices.

SUMMARY We have invented a method and associated apparatus for forming electrophoretic coating deposits selectively upon limited area and limited access sites on surfaces receptive to such deposits.

Our method is distinguished by the dispensation of a viscous coating suspension fluid at limited area and/or limited access sites through a flexible insulated nozzle or duct member which contacts the site and holds the coating fluid there, in a small viscous mass, by capillarity.

The apparatus which we have devised for carrying out the foregoing method is distinguished by its manipulatability as a hand tool, the flexibility and manipulatability ice of the dispensing nozzle attachments, the interchangeability of nozzle attachments with different shapes and opening sizes, the resilient deformability and manipulatability of the vessel Which holds the coating fluid, and the rigid electrode parts which collaterally connect the vessel and dispensing nozzle into an integral reservoir and dispensing assembly and support that assembly by threaded attachment to a rigid hand manipulatable frame support. The rigid frame support just mentioned is further distinguished by the incorporation therein of a battery compartment for supplying deposit forming voltages between the tubular cathode element and the part to be coated. The electrode and nozzle elements are distinguished further by their progressive taper towards the dispensing opening in the nozzle whereby the volume of fluid defining the shortest electrophoresis circuit path between the electrode and coating site is small.

The foregoing and other features, objects and advantages of the invention will become apparent upon considering the following more particular description of preferred embodiments of the invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation partly in section of a preferred embodiment of a hand tool constructed according to the present invention. In this view the resiliently deformable fluid storage capsule is also shown in phantom in a displaced (filling position;

FIG. 2 is a side elevation partly in section of the same tool in an exploded assembly view;

FIG. 3 is an elevation of the top of the same tool;

FIG. 4 is an elevational view of a differently shaped nozzle element interchangeable with the nozzle element shown in FIGS. 1 and 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS A preferred embodiment of a hand tool for selective electrophoretic coating in accordance with the present invention is illustrated in FIGS. l-3 with variety of interchangeable nozzles suggested by the nozzle shown in FIG. 4.

The tool includes: a vessel assembly 1 for holding and dispensing viscous aqueous coating suspensions, a conducti-ve frame 2 for holding the dispensing vessel assembly and integral with the frame 2 a battery compartment 3 for holding batteries 4 (FIG. 1) to supply the deposit forming voltages. In the particular exemplification a pair of 9 volt batteries in series supplies the 18 volts required to form consistent electrophoretic deposits.

A spring 5 (FIG. 1) supplies contact between the negative terminal of the lower battery and the conductive frame while urging the positive terminal 6 (FIG. 1) of the upper battery into contact with contact element 7 (FIG. 1). Contact element is attached by solder to conductive lead 8 and by press fitting to the insulated cap 9 which serves as a cover for the battery compartment. Lead 8 extends through opening 9a (FIG. 1) in cap 9 and terminates in a probe tip 10 (FIG. 1).

Contact for selective coating is made through tip 10 to the part 11 which is to be coated. Conductor elements 12, 13 and a not shown connection between them complete the electrical circuit path from tip 10 to selected coating site 14- Battery compartment 3 terminates in treads 15 mating with internal threads 17 in cap 9. The battery compartment also has an extended frame section 19 having an opening 20. This receives and supports the filler cap and section 21 of the vessel assembly 1.

The vessel assembly includes a deformable reservoir capsule section 23 made of flexible vinyl tubing. This section is brazed to a rigid metal member 25 having a shoulder or collar 25a and threads 26 mating with not shown internal threads in cap element 21. The lower portion of the capsule section 23 is brazed to a rigid conductive metal tubular member 28 which provides support for the vessel assembly and an electrical path for electrophoretic deposit forming currents.

Member 28 has upper threads 29 mating with internal threads 30 in an opening 31 in frame 2. The diameter of opening 31 is larger than the diameter of collar 25a of member 25, thereby permitting the vessel assembly to be inserted through the opening 31 cap end first for attachment to frame 2 by mating threads 29, 30. In this attached position collar 25a rests against frame extension 19 and cap 21 is loosely supported in the opening 20 of extension 19.

The lower end of memebr 28 is internally threaded for union with threads 32 on metallic tubular member 33. Tubular neck nection 34 of the latter member is adapted to receive flexible tubular nozzle member 35 in a tight force fit.

Vessel assembly 1 is filled with fluid by removing cap 21 and blocking the small opening 35a (FIG. 2) in nozzle 35; for example by means of the nozzle cap 36 shown in FIG. 2. The vessel may be filled with coating fluid either while it is threaded into the frame 2 or it may be filled and stored as a separate unit. When filling the vessel while in the attached position in the frame it is desirable to manipulate the deformable reservoir capsule section 23 so that the cap supporting end 25 is displaced out of and away from its supporting flange 19. In this way spillage of coating fluids over the flange 19 and into or upon the battery compartment is avoided. This displacement of capsule 23 relative to the frame is indicated in phantom in FIG. 1.

In the assembled position of FIG. 1, with the vessel assembly filled with a supply of fresh (preferably less than six months old) aqueous coating suspension and enclosed by cap 21, the nozzle cap 36 may be removed. Due to its viscosity and external atmospheric pressure the coating suspension normally will not flow out of the small nozzle opening 35a. However, when capsule 23 is compressed, for example by squeezing it manually, the coating suspension fluid can be dispensed through the nozzle in controllably small amounts.

In operation the tool is hand-held, like a pencil, with the battery compartment resting in the juncture between thumb and forefinger and the capsule 23 is gripped between the fingers. The nozzle tip 35a is placed in contact with the selected site 14 to be coated and a small amount of coating fluid is squeezed out upon the site where it is held in a small viscous mass by capillarity. This completes an electrical circuit path from battery negative to site 14 through spring 5, conductive members 2, 28 and 33, and through the fluid extending through nozzle 35 and contacting site 14. At the same time the circuit to battery positive is completed from site 14 through conductors 13 and 12, probe tip 10, lead 8 and contact 7. With the foregoing circuit completed and appropriate battery voltage applied the solids dispersed in the extruded viscous mass of suspension fluid flocculate and deposit out in a small confined area at site 14 in a thin continuous film. Thicknesses of 1 to 5 mils are typical. Suspension fluids which have been used successfully and parameters of deposition are described below.

For difficult to reach sites different nozzles may be required. An example of one such with an L-bend is illustrated in FIG. 4.

Specifics of the tool construction and process parameters are discussed next. The following is a table listing of the numbered parts of the exemplification shown in the: drawing together with an indication of relevant composition and dimensions.

TABLE Part Numbers Composition Dimensions 2, 3, l9, 7, 25, Brass Openings 20 in part 19 and 31 in part 2 3, have respectively smaller and larger diameters than collar 25a of part 25. Opening 20 is larger in diameter than cap 21. Inner bore of tubular part 34 typically is mils. Outer diameter of part 34 is mils. 9, 21 Tetrafiuoro- D0.

ethylene. Vinyl tubing (Tys I 3 Butyl Opening 35a-typ1eal diameter-60 rubber. mils. 8, 10 Copper Suspensions which have sufficient viscosity to be used with nozzle openings 35a of indicated diameter and 1-8 volt supply such as copolymer solution of polyvinylidene chloride-polyvinyl chloride and epoxy ester are disclosed in copending U.S. patent application Ser. No. 871,825 filed Oct. 28, 1969 on behalf of L. V. iAuletta, B. E. Cornish, E. P. Damm, Jr., M. A. Faigenbaurn and A-. M. Simon which is entitled Hostile Environ-ment Protection of Critical Metallic Surfaces by Electrophoretically Deposited Coatings. For suspensions which require difl'erent current voltages other than 18 volts the internal battery 4 may be bypassed by connection of an external battery negative terminal to frame 2 and connection of the positive terminal of the same external battery terminal contact 12 of the surface 13 (FIG. 1) which is to be selectively coated. Probe tip 10 may of course be replaced by an alligator clip or other connection part.

The tool described above may be used either as a field repair or touch-up instrument. It may be used also for close detail artwork, for example in drawing insulative elements of printed circuit artwork.

We have shown and described above the fundamental novel features of the invention as applied to several preferred embodiments. It will be understood that various omissions, substitutions and changes in form and detail of the invention as described herein may be made by those skilled in the art without departing from the true spirit and scope of the invention. It is the intention therefore to be limited only by the scope of the following claims.

What is claimed is:

1. Apparatus for spot application of electrophoretic coatings comprising:

a resiliently deformable fluid storage vessel assembly having a capped fill opening and an electrochemically functional dispensing duct including a flexible electrically insulated changeable nozzle member providing a constricted fluid passage terminating in a narrow opening, said member being adapted to dispense a viscous electrophoretic coating suspension fluid with capillarity;

said duct further including an electrode conductor adjacent said duct but removed from said opening, and situated to make electrical contact with fluids dispensed through said duct and said nozzle opening;

and means connecting physically with said vessel assembly and electrically with said electrode conductor for applying electrophoresis potential between said conductor and objects contacted by said dispensed fluid at said insulated nozzle opening.

2. A hand tool for spot application of electrophoretic coatings by hand manipulation comprising: a resiliently deformable hand manipulatable fluid storage vessel assembly having a main section adapted for resilient compression by hand manipulation, a capped filling opening communicating with said main section, a dispensing duct including a flexible insulated nozzle terminating in a constricted opening adapted for dispensing small amounts of an aqueous electrophoretic coating suspension with capillarity upon compression of said main section, and a rigid electrically conductive tubular member connecting said nozzle with the main section, said member providing structural support for said assembly and functioning electrically in said assembly as an electrophoresis electrode relative to objects receiving said dispensed coating suspension; said member connecting with said nozzle at a discrete distance from said nozzle opening.

3. A hand tool in accordance with claim 2 including: a hand manipulatable rigid frame support for detachably securing said tubular member and supporting said vessel assembly While permitting the said main section of said assembly to be conveniently grasped and resiliently compressed to accomplish dispensing and electrophoretic application of said coating suspension.

4. A hand tool in accordance with claim 3 including:

a capped battery compartment integral with said frame for holding a battery voltage supply; and

means connecting electrically with the interior of said battery compartment and being insulated from said frame and electrode member for completing external battery circuit between said tubular member and a said receiving object.

5. A hand tool in accordance with claim 2 wherein said nozzle is detachably secured to said tubular member to permit interchangeable use of nozzles having difierent shapes and dispensing openings.

6.. Hand-held apparatus, for containing electrophoretic solutions and for bonding small quantities of said fluid to conductive objects by electrophoresis, comprising:

an insulated flexible nozzle section of tapered generally tubular hollow construction having a constricted tip portion including a small dispensing opening for fluids and an unconstricted open end remote from said tip;

a hollow generally tubular conductive electrode section connecting with the unconstricted end of said nozzle section forming therewith an extended dispensing conduit and applicational vehicle for elec trophoretic fluids;

a compressible generally tubular hollow container section closed at one end and connecting at the other end thereof with the end of said electrode section remote from the unconstricted end of said nozzle section to form an extended fluid containing compartment with said nozzle and electrode sections;

said container section including a detachable filler cap element forming closure of said one end and filling opening for the said extended compartment formed by said connected container, electrode and nozzle sections;

means connecting electrically with said electrode section for completing an electrochemical circuit between a conductive object adjacent the exterior of the nozzle tip and said electrode section through a fluid extending continuously from the interior of said compartment through said nozzle dispensing opening into contact with said conductive object;

said nozzle dispensing opening being sufliciently small to restrict flow of said contained fluid through said opening when said container section is not in a state of compressive tension.

7. Apparatus according to claim 6: wherein said means connecting electrically with said electrode comprises a hollow support structure forming a gripping handle for hand manipulation of said apparatus and including in the interior thereof an integral battery compartment providing electrical continuity between battery voltage of one polarity and said electrode section; said support structure including a removable cap containing an attached Wire insulated from said one voltage polarity and connecting battery voltage of opposite polarity from said battery compartment to said conductive object.

8. Apparatus according to claim 7 wherein said support structure includes an extension having an opening designed to receive and support a portion of said container section removed from said electrode section.

9. Apparatus according to claim 8 wherein said container section is both flexible and resiliently compressible and is adapted to be flexed out of position relative to said support extension opening, without disassembly of said apparatus, such flexure serving to avert spillage of fluid upon said support and battery compartment during filling of said container section with fluid.

10. Apparatus according to claim 9 wherein the assembly formed by said support structure-including said battery compartment and container supporting extension-- and said connected container, electrode and nozzle sections is designed to be hand-held and physically and electrochemically manipulated relative to said object as an integral unit.

References Cited UNITED STATES PATENTS 1,550,048 8/ 1925 Ruben 204-2 X 1,892,099 12/1932 Cornell 2042 2,316,340 4/1943 Kohn 204-2 2,365,539 12/ 1944 Flowers 204143 2,421,027 5/1947 Isaacson 204271 2,698,832 1/1955 Swanson 204'16 X 3,399,121 8/1968 Klein 2042 JOHN H. MACK, Primary Examiner A. C. PRESCOTT, Assistant Examiner US. Cl. X.R. 204181, 300 

